Medical washers are conventionally known and are used to clean instruments and equipment that are exposed to biological contaminants. Such washers typically clean the instruments and equipment by directing jets or streams of fluid at the instrument and/or equipment from spray heads or nozzles located within the washer. A typical cleaning operation may include a preliminary rinse cycle, a pre-wash cycle, and a wash cycle (where the instruments and equipment are exposed to one or more chemical cleaning solutions), a rinse cycle and a thermal rinse cycle.
During these various phases of a washing cycle, fluids are introduced into the washing chamber by pumps to effect the washing or rinsing of the articles to be cleaned. The fluids used within the washing chamber during the different cycles often have significantly different temperatures. For example, during a pre-wash phase, cold water from a facilities' cold water lines (i.e., tap water) is typically used. The wash phase typically uses water (with added detergents and chemicals) from the facilities' water lines, the water being heated within the washing chamber to about 150° F. (The heating of fluids within the washer typically occurs in a sump located at the bottom of the washing chamber where the washing fluids are collected). The rinse phase typically uses hot water from the facilities' hot water line. A thermal rinse typically uses pure, high-quality water that is heated within the washer to about 190° F.
The use of hot and cold fluids within the washing chamber during the different phases of the washing cycle, as well as the starting and stopping of pumps, can produce significant fluctuation in pressure within the washing chamber between the different phases of the washing cycle. More specifically, changes in temperature of the fluids used during the different phases of a washing cycle and the starting and stopping of pumps can produce either an increased pressure in the washing chamber, as compared to the surrounding environment (i.e., a positive pressure), or a vacuum within the washing chamber as compared to the surrounding environment (i.e., a negative pressure). These occurrences are referred to as “thermal shock.”
To reduce “thermal shock” during operation, washers/disinfectors known heretofore typically include a two-speed motor to pump washing and rinsing fluids through the washer/disinfector. The two-speed pump operates at a low speed during the initial start of a cycle phase to introduce the fluid into the washing chamber at a low rate to minimize the thermal shock created in the washing chamber during the start-up procedure.
The aforementioned types of washers/disinfectors having two-speed motors are typically used in large hospital and medical facilities. However, there is also a need for a less expensive, instrument washer for small clinics and one-day surgical centers. To help reduce the cost of a washer/disinfector for small clinics and one-day surgical centers, use of a one-speed pump is desirable.
The present invention provides a washer/disinfector having inlet diffusers to distribute fluids entering a washing chamber during operating phases to reduce the thermal shock that may occur during a washing cycle.